A conventional elevator system includes an elevator car that travels through a hoistway. The travel path of the car is defined by a pair of guide rails that extend longitudinally through the hoistway. The car is engaged with the guide rails by guide rollers that roll along the guide surfaces of the rails.
In one type of such elevator system, the elevator car is mounted in a cantilevered arrangement in order to minimize the space requirements of the elevator system. In this type of mounting arrangement, the guide rollers include an upper pair of rollers and a lower pair of rollers. The upper rollers are located on the side of the guide rails opposite the elevator car and the lower rollers are located on the same side of the guide rails as the car. As a result, the guide rollers are exposed to reaction forces caused by the loading of the car.
A drawback to the cantilevered type arrangement is the deformation of the guide rollers caused by the reaction forces. One particular problem is that the rollers, which typically have a contact surface formed from an elastomeric material, become deformed during extended periods of non-use. When the car is parked for an extended period of time, the reaction forces are concentrated on the portion of the elastomeric material in contact with the guide rail. As a result, the elastomeric material deforms and a `flat` area develops in the roller. During subsequent operation of the elevator system, the flat portion of the roller produces vibration that is perceptible by and discomforting to the passengers riding the elevator. This is a particularly significant problem for the lower rollers of the cantilevered cars.
The above art notwithstanding, scientists and engineers under the direction of Applicants' Assignee are working to develop methods and apparatus to improve and maintain the ride quality of elevator systems.